Exhaust gas purification system

Abstract

An exhaust gas purification system which purifies exhaust gas discharged from an internal combustion engine includes an exhaust pipe, an electrochemical reactor and a cooler. The exhaust gas flows through the exhaust pipe. The electrochemical reactor is mounted to the exhaust pipe and has a polyelectrolyte membrane. The cooler is provided at a position that is upstream of the electrochemical reactor for cooling the exhaust gas.

1 . An exhaust gas purification system for purifying exhaust gas discharged from an internal combustion engine, comprising:
 an exhaust pipe through which the exhaust gas flows;   an electrochemical reactor mounted to the exhaust pipe and having a polyelectrolyte membrane; and   a cooler provided at a position that is upstream of the electrochemical reactor for cooling the exhaust gas.   
     
     
         2 . The exhaust gas purification system according to  claim 1 , further comprising:
 a bypass pipe connected to the exhaust pipe at a position that is upstream of the electrochemical reactor for allowing the exhaust gas to flow to the electrochemical reactor through the bypass pipe; and   a selector valve mounted to the exhaust pipe for selecting the flow of the exhaust gas either through or not through the bypass pipe,   wherein the cooler is mounted to one of the exhaust pipe and the bypass pipe.   
     
     
         3 . The exhaust gas purification system according to  claim 2 , wherein the selector valve is mounted to a connecting point of an upstream end of the bypass pipe and the exhaust pipe. 
     
     
         4 . The exhaust gas purification system according to  claim 2 , further comprising:
 a control unit is provided for controlling the selector valve based on a temperature of the exhaust gas.   
     
     
         5 . The exhaust gas purification system according to  claim 4 , further comprising:
 a sensor is mounted to the exhaust pipe at a position that is upstream of the selector valve for measuring the temperature of the exhaust gas and outputting a signal of temperature to the control unit.   
     
     
         6 . The exhaust gas purification system according to  claim 4 , wherein the control unit has a data map for representing relation between operating condition of the internal combustion engine and the temperature of the exhaust gas, wherein the control unit estimates the temperature of the exhaust gas from the operating condition in accordance with the data map. 
     
     
         7 . The exhaust gas purification system according to  claim 1 , wherein cooling water flows though the cooler, wherein the exhaust gas is cooled by heat exchange with the cooling water in the cooler. 
     
     
         8 . The exhaust gas purification system according to  claim 1 , wherein the cooler has a concavo-convex portion formed on an outer periphery of the exhaust pipe at a position that is upstream of the electrochemical reactor.